The invention relates to intraocular lenses, whether designed for anterior-chamber implantation or for posterior-chamber implantation in the human eye, and whether or not iris-supported.
As far as I am aware, with the exception of my constructions, prior intraocular lenses have been of plastic construction, and they are tissue-reactive in the sense that tissue growth after implantation is not retarded and can become a clouding factor to degrade optical performance of the implant. With such plastic lenses, sterilization must be accomplished using a caustic solution or ethylene oxide gas.* Such lenses are injection-molded products and therefore cannot be classed with the quality of an optically finished lens. But glass lenses as implants have been generally shunned, primarily because of the high specific gravity of glass, as compared to that of plastic; see Binkhorst, et al., "A Weightless Iseikonic Intraocular Lens", American Journal of Ophthalmology, Vol. 58, No. 1, July 1964, pp. 73 to 78. And, in particular, it is noted that although Choyce, et al., U.S. Pat. No. 4,087,866 mentions glass as a possible lens material, the disclosure is silent on any suggestion of optically finished glass for the purpose. FNT * A glass lens would allow for autoclaving. To my best knowledge and belief, the difficulties and expense of making molds for plastic intraocular lenses have meant that the implanted lens must be simple and basic, reliance being placed upon later prescription of corrective spectacles if astigmatism is to be corrected in an individual case.